Calling device for wireless telegraphy



July 2, 1929. .w. J. DAvls CALLING DEVICE FOR WIRELESS TELEGRAIHY Filed Nov. 3, 1921 2 Sheets-Sheet f/gf WIW-ill" gvwentoz W. J. DAVIS 3.1).., hiawwyQ/m.

July 2, 1929.

w. J. DAvls CALLING DEVICE FOR WIRELESS TELEGRAPHY Filed Nov. 3, 1921 2 Sheets-Sheet 2 Patented July 2, 1929.

UNITED STATES PATENT'OFFICE.

WILFRED JOHN DAVIS, OF PLYMOUTH, ENGLAND, ASSIGNOR TO RADIO CORPORATION V OF AMERICA, A CORPORATION OF DELAWARE.

CALLING DEVICE FOR WIRELESS TELEGRAPHY.

Application led November 3, 1921, Serial No. 512,439, and in Great Britain December 20, 1920.

The dbject of this invention is to provide improved apparatus by which an alarm can be automatically given on the receipt of a predetermined combination of Morse characters such as the international distress signal S. O. S. (0 forexample although the arrangement may be adjusted to respond to any prearranged combination.

According to this invention a relay A is provided in a receiving circuit, say, in the anode circuit of a valve (not shown), and cach time this relay is closed a current is caused to pass through a slow acting relay B which only closes for a dash butnot for a dot. This slow acting' relay B controls the.

circuit of an electromaguet D which is accordingly only energized by dashes. In parallel with the slow acting relay is a second elect-romagnet F energized by both dots and dashes, and in series with both the electromagnets D and F is a set of contacts all of which shortcircuit a bell or other alarm. The two electromagnets D and F are arranged to open these contacts so that when the predetermined combination is received all the contacts are opened and the bell or other alarm will be actuated, but this will not occur unless the predetermined combination is received.

The shortcircuiting of the bell or other alarm is controlled by means of the following apparatus A ratchet wheelhaving fast with it a disk is turned one tooth by the second electromagnet F each time it is energized, that is, for each dot and each dash. Around the periphery of the disk are arranged spring plungers which can move parallel to the axis and the number of which is equal to the number of teeth on the ratchet wheel. Adjacent to each plunger is a spring finger pivoted to the disk and adapted, on any plunger being moved outwards from the face of the disk to slip in under the head of the plunger to lock and keep it protruding from the face of the disk. As the disk is rotated these plungers pass in turn before ithe armature lever D of the first electromagnet D with the result that whenever that magnet is energized by .the receipt Vof a dash. a plunger is moved outwards from the face of the disk and its locking finger slips behind its head and keeps it out. Just before a plunger is carried by the rotation of the disk past the first magnet the end of its locking finger comes against a fixed stop K or N which withdraws any inger that may happen to be beneath the head of a plunger and thus allows the plunger to be returned by its spring to its normal position. On the receipt of the predetermined combination, say, S. O. S. there will be a sequence of plungers on the disk in the following order: Three in, three held out, three in. Opposite the plungers of this sequence in the position they occupy as soon as the sequence has been completed is an equal number of spring contact plungers carried by a fixed bracket. The middle three rcontact plungers control three of the short eircuiting contacts G which are normally closed and these three will be pushed out by the heads of the protruding plungers at the middle of the sequence that has been set up on the disk and therefore these three contacts will be opened. The other contact plungers Q on the bracket are adapted to make electrical connection with the head of anyl protruding plunger I which may be opposite them, that is, the six dot contacts are normally open but are closed when there is a protruding plunger on the disk opposite one of the six plungers on the bracket. When, however7 the required sequence has been set up none of the plungers I on the disk opposite the six plungers Q, onthe bracket will be protruding and therefore all the nine contacts will be open and the bell or other alarm will be actuated. Unless, however, the predetermined combination of signals has been received some one or more of the contacts will be closed and therefore the bell or other alarm will not be actuated. When all the contacts are open the bell or other alarm which had previously been shortcircuited is connected in series with the second electromagnet F and the current through this magnet is thereby reduced sufficiently to prevent any further rotation of the ratchet wheel and disk'. The. contacts therefore remain open and the alarm continues to be actuated so long as signals are received.

In place of the first electromagnet attract-` ing a plunger `it may be caused to actuate a spring lever which pushes the plunger outwards from the disk as shown in Fig. 2.

The slow acting relay may be an ordinary electromagnet having stout copper bushes around the pole tips, so that the eddy currents set up in the copper retard the building up of the magnetic flux.

If it is desired to include in the sequence which is to give the alarm the necessary inter-letter spaces at the beginning and end of the S. O. S. signal, a slow acting space relay C may be provided to control the circuit of an electromagnet E which will only be energized by inter-letter spaces and not by the spaces between the elements of a letter.

The following detailed description and accompanying drawings show one way the apparatus could be arranged to give an alarm on receipt of the International distress signal c) preceded and ended by a space not shorter than the space between letters of the Morse code; the complete signal could therefore be written down as space, dot, dot, dot, dash, dash, dash, dot, dot, dot, space.

The invention is illustrated by the accompanying drawings, Fig. 1 of which is a diagram showing the connections, Fig. 2 is a side elevation in partial section of the apparatus, Fig. 3 is a face view of the disk along the section line III. III. of Fig. 2, Fig. 4 is a rear View of the apparatus and Figs. 5 and 6 are sections on the lines 5-5 and 6-6 of Figure 4. Figure 7 is a diagram showing a modification.

In Fig. 1 A is a signal relay the coils of which are in the anode circuit of a receiving valve so that the tongue T follows the dots and dashes of the incoming signals. In series with the tongue T and marking contact M of this relay is a delayed action marking relay B connected to a battery A, while connected in serieswith the tongue T and spacing contact S is a delayed action spacing relay C also connected to the battery A. The contacts of these delayed action relays B and C do not close until some little time after the contacts T and M and T and S respectiva,

ly close. The relay B is adjusted to close for a dash and not for a dot, while the relay C is adjusted to close when a space at least equal to that between letters is received but to remain open for the shorter spaces between elements of a letter. In series with the contacts of relays B and C are two electromagnets D and E; it will be seen that D, the dash magnet, is only energized when a dash is received, while E, the space magnet, is only energized when an inter-letter space is received. Also connected in series with T and M and in parallel with relay B is a ratchet controlling magnet F which is operated whenever T contacts with M. A number of contacts G in parallel withI a bell X or other form of alarm or recording device connected across them are inserted in series with B, C, D, E and F, therefore every time contacts T and M of the signal relayy A close, a current will flow round the coils B andF and across such of the contacts at G as are closed. If the contacts T and M remain closed for a longer period than is represented by a dot then the contacts of relay B close and D is energized. When contacts T and S close them the/circuit through B, D and F is broken, lwhile a current passes through rela C and across contacts G; if contacts T and C remain closed for a longer period than is represented by the space between the dots or dashes of a letter, then the contacts of C close and magnet E is energized. So long as one or more of the contacts at G are closed the bell is short circuited and cannot ring but when all these contacts G are open the current passes through the bell which therefore rings when the contacts T and M or T and S of relay A close.

An arrangement for controlling the contacts G is shown in Fig. 2 in which H is a disk which is preferably made of aluminum to reduce its momentum and which has a number of plun ers I, 1 to 24 fitted round its periphery. Eac plungerl is kept in position by a spring J under compression which pulls the head of the plunger on to the face of the disk. The disk is fast on a spindle O which has also fast with it a ratchet wheel L having Y a number of teeth (24) equal to the number of plungers on the disk; a pawl P operated by the magnet F engages with this wheel and every time the tongue of relay A returns to its position of rest after having been moved by a dot or dash, that is to say, every time the contacts T and M open, the disk H is rotated through one tooth of the wheel L.

Pressed against the head of each plunger by a spring 1' is a light locking finger R Fig. 3) so that when a plunger is pushed outward from the disk the finger R will slip in under its head and so prevent the plunger from re-A turning to its normal position when released.

When either of the'magnets, D, E, is enl ergized its armature D or E pushes the plunger I which is opposite it outwards from the face of the disk H. When the magnet is de-energized the armature releases the plunger but its finger R has, however, by this time slipped in under the head I of the plunger so that the plunger cannot return to its normal position but remains projecting from the face of the disk. Every plunger is reset to its normal position by the fixed stops K and N immediately before passing in front of either of the armatures.

It is requid that the alarm bell shall ring after the signal c 0 0 has been received. Before the first dot commences there is a space; that means that the tongue T and spacing contact Sof the relay A are closed for an appreciable period so that the contacts of the delayed action spacing relay C close. The space magnet E is therefore energized and let us assume that plunger I is pushed outwards by the space lever or ar- CTI mature lever E and locked by its finger R. As soon as the signal commences the contacts Tand S open .and the spacelever or armature is released and remains so until the end of the signal and the plungers I2 to 110 which rotate in a counter-clockwlse direction as indicated in Figure 3, and passed by" armature E are not actuated. When the space after thel last dot occurs the plunger I10 is actuated. The first three dots of the signal close the contacts T and M of relay A three times and i after each dot is completed it causes the disc H to be rotated through one tooth of the Aratchet wheel L by closing the relay F without the operation of the dash relay offfthe movement of plungers 113,114, 115; now when the rst dash comes alongf the contacts of the relay Blo'se, this causes the dash ma et D to be energized and the plun er 1 Wixch is in front of'D is therefore pus ed outwards from the disc. Whenv the dash ends the disk is rotated through one tooth. The other two f dashes act similarly to push plungers IH, Il, outwards. The last three dots cause the disk to be rotated through three teeth and plungers 11 I2, and I21 are not affected because the dash ma et is not energized. A dot merely causes t e disk to b e subsequently rotated through one toothof the ratchet wheel, while a dash causes a plunger to be pushed outwards as well as siibsequentlyvrotating the disk throu h one tooth. As soon as the signal is finisied, .the s ace at the end causes the contacts Aof the de ayed action spacin re- C tol close and the plunger 1 in ront la ofy the armature spacing magnet is pushed outwards. Hence, after the signal o o j e o )has been received the five shaded plungers 11,110, 1,6, 11 11s as shown in Figure 3, will project from the face of the disk.` The other plungers corresponding to the dots and tothe short inter-element spaces between the dots and dashes of the signal are in their normal position.

j If an deviation in spacing or signalling occurs, owever, even if it effects only asingle plunger to move it out of proper position,

I `the arrangement of switches on the insulating bracket V- will prevent the current from flow-ing through the bell X and it will be necessary to start a new series of signals of the proper sequence. Plungers 111,112, 123,

vand I2, are extra lungers and in the illustration given, no s ort circuiting devlces are used in conjunction therewith. In front of the disk H is a fixed insulated bracket V,

Figure 4, carr ing 24 spring contact plungers Q. Five o these contact plungers, which occupy positions corresponding to the shaded plungers in Figure'3, cause, spring contacts B to be normally closed as shown in Fig. 5 so that any projecting plungers which l pass in front of `them tend to open these contacts, while'the remaining@ contact plungers as shown in Fig. 6 ma e electrical contact magnet sufficiently to with the heads of any ro'ecting plungers 1 on disk H which ass1n ront of them, i. e. these 19 contacts etween plungers I and-Q are normally open 'and only closed when ,there is a plunger I projecting in front thereof.. All these 24 contacts are joined in parallel and are the contacts represented diarammatically at G, Fig. I. It will therefore be s een that when the correct signal has been-received giving the vdisposition of the plungers, as shown in Fi 3, all the 24 contacts are open, the three dash and two space contacts being uslled open by the projecting plungers in ront of them, while the remaining 19 'contacts are open because 80 there are no projecting plungers in frontof them. When all these contacts are open, the bell X which has previously been short circuited is connected in series with the magnet F. This-reduces the current through this S5 reventl any further rotation of the disk H. he contacts C therefore remain open and the bell rings every time the contacts T and M or T and S of the signal relay A close; if the `sending continues'Qo the bell rings out 'the incoming signal while if the sending stops the bell rings continuously. Itis obvious that this explanation has been applied to specifically mentioned plungers J5 only for the purpose of illustration. Any one .might be the first in the signal series, since, after the plungers have passed either stop K or yN theyare restored to their normal position. 1t is apparentth-at while any sig- 100 nals are being received that the disc H is in constant rotation but the bell is not energized because the proper combination and se uence is not obtained. 1n case of this S. O. signal described, the lastthree plungers haveno function so that the position of the first nine counting from the stops K and N are the ones Jvwhich control. From this it is seen that a continuous operation is maintained and no at- `tention is required when once. the'device is 110 placed in operation.

After the bell has been operated to sound the alarm the lapparatus may be reset by isimplypushing in one of the short circuiting switches as at G which allows suliicient cur- 11.5

nary electro-magnet lwhich has Stout co r s Ppe bushes round thepole tips. 'Ihe edd :currents set up in the copper retard the building of the magnetic flux- The armature of the relay is therefore not attracted until some little time after the current is started through the windings. This type of relay works satisfactorily so long as the current through the windings remains constant; if, however, the

vsupply voltage increases or decreases by a and 2 and 4 make contact. 2 therefore follows the dots and dashes ofthe incoming sign' nal connected in parallel with relay 1 but also in .series with 2 and 3 is a second rela B whose tongue 5 is normally in contact withI a contact 6. A coil D which it is required shall only be energized by a dash is connected in series with the Vcontacts 4, 5`and 6. The action is as follows:

Suppose T and M close for a period represented by a dash, a current passes through relays 1 and B andthe tongues 2 and 5 innnediately commence to move downwards; as soon as 2 and 3 separate, however, the circuit through relay B is broken so that 5 is free to move back again. After an interval of time epending on the inertia of the tongue and the tension of its restoring spring 5 and6 will again make contact. 2 and 4 are already in `contact and a current therefore passes through the coil D. Now sup ose the contacts T and M are only close for a short period represented bya dot; as soon as T and M close the same thing happens as before, viz: 2 moves instantly over to 4 and 5 moves away from 6 and then back again, but before 5 and 6 make contact the dot has ended and T and M and consequently 2 and 4 have opened, no current therefore passes through coil D.

The delay with thisarrangementis the time taken by tongue 5 f relay 6 to make one swing, this is governed by the inertia of the tongue and the tension of the restoring spring.

-Ifin addition to the coil to be ener 'zed by dashes it is necessary that coil E of igure 1 should be energized when a space ual to the interval between letters is receive a back contact S is provided for the tongue T so that a spacing relay may be energized when tongue T makes contact with S to control the space magnet E. v y

Having described my invention, what I- claim is':

1. In an electric calling device, in combination, a main relay adapted to be actuated by incoming signals, a slow-acting relay controlled by the main relay, an electromagnet controlled by the slow-actin relay, a second electromagnet in parallel with the slow-acting relay, a set of normally closed contacts in series with both electromagnets, means whereby said contacts are selectively controlled by the magnets in accordance with the length of the received impulses,- and an alarm shunted by said contacts, so that opening of the set of contacts by the electromagnets actuates the alarm. Y

2. `In an electric calling device), in combination, an electromagnet energized by impulses corresponding to dashes only, a second elecitromagnet energized by impulses corresponding to both dots and dashes, a set of normally closed contacts in series with both electromagnets, means whereby said contacts are selectively controlled b the magnets in accordance with the length ofY the received impulses, and an alarm shunted by said contacts, whereby upon opening of said contacts by the electromagnets the alarm is actuated. P

3. In an electric calling device, the combination lof an alarm and a magnet which is energized by relatively long electrical impulses only, a second ma et which is energized b both relatively on and relatively short e ectrical impulses a t 'rd magnet responsive to time intervals of relatively long duration, a disk carrying round its periphery a set of plungers, means operated by the first magnet to cause certain plungers to protrude from the disk, means actuated by the second magnet for rotatin the disk through the angle between two p ungers, means actuated by said' third named magnet to cause certain other plungers to protrude from said,L disk .andla set of contacts operatively associated with said plungers and said alarm.

4. In an electric calling device, the combination of an alarm and af magnet which is energized by relatively long electrical impulsesl only,' secondmagnet which is energized by both relatively long and relatively short electrical impulses, `a disk carrying round its periphery a set of plungers, means operated by the first ma et to cause plungers to protrude from the ilsk, means actuated by the second maxet for rotating the disk through the angle etween two plungers and a set of contacts which are controlled by the plungers and which short circuit the alarm, another magnet energized on the occurrence of an inter-letter space to actuate some of the plungers on the disk. a

5. In an electric calling device, the combination of an alarm and a magnet which is energized by relatively loiig electrical impulses only, a second ma et which is energized by both relatively nng and relatively short electrical impulses, a disk carrying round its periphery a set of plungers, means operated by the first magnet to cause plun ers to protrude from the disk, means actuate b lthe second ma et for rotatin the dis through the angle between two p ungers and a set of contacts w hich are controlled b the"` plungers and which short circuit the a arm,

fingers carried by the disk adapted to lock the plungers and hold them protruded against spring action whereby they are maintained in proper sequence according to the sequence of the signal. Y

6. In an electric calling device, the combination of an alarm and a magnet which is energized by relatively long electrical impulses only, a second magnet which is energized by both relatively long and relatively short electrical impulses, a disk carrying round its periphery a set of plungers', means operated by the first magnet to causeplun ers to protrude from the disk, means actuate by the second magnet for rotating the disk through the angle between two plungers and a set of contacts, shunting said alarm, con-v trolled by said plungers, the set ofcontacts being so arranged in front of the disk that some contacts are normally closed while others are normally open.

7. In an electric calling device, in combination, an alarm, a magnet energized by im- Y pulses corresponding to dashes only, a sec`l ond magnet energized by impulses corresponding to both dots and dashes, a set of contacts normally short-circuiting ,said alarm, plungers associated With said contacts, some of which are controlled by the two magnets, and another magnet for controlling other of said contacts -by means of-said plungers, said. last mentioned vmagnet being energized only on occurrence-of inter-letter spaces;

8. In combination, a step by step rotating? element, means for rotating the element a Y step each time an element of a signal is received, sliding means carried by theelement, l switching means carried on a stationary part and affected by the sliding means, actuating means controlled by certain signals and .in-

.tervals between signalsv .for Aactuating the `sliding means, locking means adjacent the sliding means for holding said sliding means in actuatedp'esition and means for rendering said locking. meansinoperative..

9. AIn combination, a step by step rotating element, (means for rotating the element a step each time an, element of a signal is received, sliding means carried bythe element, switching means carried on a stationary part and affected by the sliding means, actuating means controlled by certain elements of the signal for actuating the sliding means, lockinfr means adjacent the sliding means for holding said sliding means in actuated position over a period of rotation .of tlie rotating element, and releasing means for unlocking.

the locking means to release the slidingmeans to its original position for canceling the ef fect of incorrect signals, said releasing means determining the locking period 'of 'the locking means. .A

Y 10. In combination, a. step by step rotating element, `means for 'rotating the element a .step each time an clment of a signalis ref` ceived, sliding means carried by the element, switching means carried on a stationary part and affected by the sliding means, actuating means controlled by-certain elements of the signal for actuating the sliding means, lockingmeans for the sliding means to hold the sliding means in actuated position over a period of rotation of the rotating element, and releasing means for unlocking the locking means to release the slidingmeans to its original position for canceling the effect of incorrect signals, said releasing, means determining the locking period of the locking means, the switching means being so arranged as to produce a change of circuit conditions only when actuated by a proper sequence of si nal elements throughthe sliding and loc ing means. l

11. In combination, astep by step rotating element, means for rotating the elementa step each-time an element of a signal is received, sliding means carried bly the element, switching means carried on a stationary part andv effected by the sliding means, actuating means .controlled by certain elements ofthe signal for actuating the sliding means, lockin g means for the sliding means to hold the sliding means in actuated position over a period of rotation of the rotating element, releasing 'means 'for' unlocking the locking means to release the sliding means to its original position for canceling the effect of incor- -rect si nals, the switching means being so arrange as to produce a-cha-nge of circuit conditions only when actuated by a proper sequence of signal elements through the sliding and locking means, and alarm means operated by the switching means in response lto change of circuit conditions. v

12.#Inan electric calling. device, in combij nation, a relayactuated by incoming signals,

a slow acting relay controlled by the first re.- lay, a magnet controlled by said slow acting relay, a second magnet in parallel with `the slow actingrelay, a set of contacts inseries with both magnets, a signallingcircuit including a source -of power and an alarm normally short circuited' bythe -set of contacts, and means controlled by said magnets in accordance with the signal impulses and intervals for'relatively positioning the contacts of theset to remove -the` short circuit whereby "the Aalarm-is rendered operative.

13. In an electrical calling device, in Acombinatin, a relay .actuated by incoming signals,y aslowactingrlay controlled by the rst relay, a magnet controlled by said slow acting `relay, a-second magnetparallel with the slow acting relay, a of contacts in series with .both magnets, a 'gnalling circuit including a source of, power and an-.alarm normally short circuited by saidset of contacts, andmeans operatively interposed beipo determined series of signals and intervals to position the contacts of the set to remove the short circuit and render the alarm operative.

14. In an electric calling device, the combination of a signalling circuit including a source of power'` and an alarm, a magnet energized .by impulses corresponding to dashes only, a second magnet energized by impulses corresponding to both dots and dashes, a set of contacts in series with both magnets and normally 'short circuiting said alarm, and

means associated with said contacts and said magnets and controlled by said Vmagnets for rclativelypositioning the contacts of the set to, remove the short circuit whereby the alarm is rendered operative. 15. In a signalling device, a signalling circuitincluding an indicating device and a source of power, means for normally short circuiting s aid indicating device including a plurality of normally closed contacts, a signal relay, a slow acting, spacing relay associated therewith,.a spacing magnet associated with said spacing relay, a-slow acting marking relay associated with said signal relay, a dash magnet associated with said marking relay, a ratchet control Amagnet in 'parallel with said slow marking relay, a rotatable disk, a ratchet wheeled integral with said disk, a ratchet interposed between said ratchet control magnet. and said ratchet contacts, an armature interposed 'between' said dash magnet and the periphery of said disk, a second armature interposed between said space magnet andthe periphery of said disk and means operated by said armatures in response to'a predetermined signal for rol tating said wheel and operating said plungers to open all of said contacts.

16. In a signalling device, a signalling circuit including a source of power and indicating means, a plurality of contacts normally short circuiting said indicating means, a signal relay, switching means associated therewith,

mean's'associated with said switching means' and said relay and responsive to vtime intervals of a predetermined duration to disassociate predetermined ones ofsaid sho-rt circuiting contacts, a slow acting relay associated with said signalled relay and with lSaid switching means, and means including means operated by said slow acting relay in response to signalled impulses of predetermined duration to disassociate the remaining ones of said i short circuit contacts.

WILFRED JOHN DfAvIs.

determined series of signals and intervals-to position the contacts o the set to remove the i short circuit and render the alarm operative.

14. In an electric calling device, the combination of a signalling circuit including a source of power. and an alarm, a magnet energized by impulses corresponding to dashes only, a second ma et energized y impulses corresponding to oth dots and dashes, a set of contacts in series with both magnets and normally 'short circuiting said alarm, and

means associated with said contacts and said relay, a ratchet control magnet in parallel with said slow markin relay, a rotatable disk, a ratchet wheele integral with said disk, a ratchet interposed between said ratchet control magnetand said ratchet wheel, a plurality vof plungers slidably located around the periphery of said 'rotatable disk cooperating withV said normally) closed contacts, an armature interposed etween said dash mavnet and the periphe of said disk, a second armature inter-pose between said space magnet and the periphery of said disk and means operated by said armatures in response to'a predetermined signal for rotating said Wheel and operating said plungers to open all of said contacts. y

' 16. In a signalling device, a signallin circuit including a source of power and in icating means, a plurality of contacts normally shortcircuitingsaidindicatin means,asignal relay, switching means associated therewith,

means'associated with said switching meansand said rela and responsive to time intervals of a predetermined duration to disasseciate predetermined ones of said short circuiting contacts, a slow acting relay associated (with said signalled relay and with Said switching means, and means including means operated b said slow acting relay in response to signalle impulses of predetermined duration to disassociate the remaining ones of said A short circuit contacts.

WILFRED JOHN DAVIS.

CERTIFICATE 0F CORRECTION.

Patent. Nb. 1,719,535.

crime my z. y1929, to

warnen JoaN DAVIS. i

It is hereby certified that error. appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, linel 98, claim Il, afterthe word "signals" the locking period of the locking means;

insert the words "said releasing means determining and that the seid Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

signed and sealed this rsa1 any of February, A. n. 1930.

(Seal) M. J. Moore, Acting Commissioner of Patents. 

